1. Field of the Invention
The invention relates to novel 5-fluorouracil derivatives, which are orally applicable anti-tumor agents.
2. Description of the Prior Art
5-Fluorouracil (hereinafter abbreviated as 5 FU) has widely been used in treatment of malignant tumors as antimetabolic anti-tumor agents. The anti-tumor activity of 5 FU is very strong, but it has many disadvantages such as the restricted scope of application, limited dosage, forbidden continuous administration over long periods and difficult oral application because of its strong toxicity and adverse reaction of frequent occurrence. As a modified 5 FU derivative, FT-207 [1-(2-tetrahydrofuryl)5-fluorouracil] [Ftorafur.RTM. (Taiho Yakuhin); Jap. Pat. Unexam. Pub. Nos. 50-50383; 50-50384; 50-64281; 51-14682; 53-84981] which is a less toxic, orally and continuously administrable derivative, the activity of which is, however, insufficient, is now commercially available. Other 5 FU derivatives under clinical evaluation, for example, HCFU [1-n-hexylcarbamoyl-5-fluorouracil] [Mitsui Seiyaku; Jap. Pat. Unexam. Pub. No. 50-148365] are known.